The objective of this research is to determine the molecular mechanisms of B-cell activation through the use of cloned antigen-specific lymphoma lines and molecularly defined, B-cell activation factors. Antigen-specific B-cell lines will be obtained through the preparation of B-cell hybrids and gene transfer of oncogenes. Parent lines in the hybridization experiments will include pre-B cells transformed by Abelson virus and B lymphomas that are chemically or spontaneously transformed. Lymphoma and viral oncogenes will be used to transform antigen-specific B cells by gene transfer. Viruses to be used are Abelson leukemia virus, Rous sarcoma virus, Fujinami sarcoma virus, avian myelocytomatosis virus MC29, Moloney sarcoma virus, and SV40. Specific emphasis has becn placed on transformation with temperature-sensitive viruses so that the study of clonal cells with a normal phenotype at the nonpermissive temperature will be possible. The functional responsiveness of the antigen-specific B-cell lines will be determined through the use of antigen and B-cell activation factors. The delineation of the intracellular molecular mechanisms of B-cell activation in the antigen-specific B cell lines will be initiated by determining the changes in individual cellular proteins, in protein phosphorylation, and in T200 surface antigen expression. These changes will be monitored at each stage of the activation sequence. (LB)